Qantas, Air NZ jets in near miss
Join Date: Jan 2001
Location: NSW Australia
Posts: 233
Likes: 0
Received 0 Likes
on
0 Posts
Otto:
Verbatim, the note in the FCOM says, "If positive visual verification is made that no obstacle or terrain hazard exists when flying under daylight VMC conditions prior to an obstacle or terrain warning, the alert may be regarded as cautionary and the approach may be continued."
Therefore the relevant points are:
1) It is not necessary to "brief" the possibility of a GPWS warning to continue the approach - the pilot only needs to have assessed (in day VMC conditions) that there is no threatening terrain in the vicinity of the approach path.
2) In all other scenarios (night and/or IMC), any GPWS warning must be followed - even if familiar with the local area.
WRT the level-off altitude following a GPWS warning, the recovery actions state:
"Monitor radio altimeter for sustained or increasing terrain separation."
"When clear of terrain, slowly (my bolding) decrease pitch attitude and accelerate."
Remember that when the GPWS warning profile is flown, the aircraft will be at a very high pitch attitude with maximum thrust set. Even if initiated very early, a level-off that would not cause a very uncomfortable bunt would use a considerable ammount of airspace.
There is no "upper limit" to a GPWS recovery manoeuvre. While the highest MSA at Auckland is 3400 feet, even if the pilot initiated the recovery at this altitude it is likely that a much higher altitude would have resulted following the level-off (for the reasons already given). Our Limitations manual tells us that: "Pilots are authorised to deviate from their current ATC clearance to the extent necessary to comply with an EGPWS warning." Therefore, if a GPWS warning was received, it would supercede any previous ATC altitude instruction.
Further guidance from the manuals is that GPWS warnings take precedence over TCAS advisories.
Verbatim, the note in the FCOM says, "If positive visual verification is made that no obstacle or terrain hazard exists when flying under daylight VMC conditions prior to an obstacle or terrain warning, the alert may be regarded as cautionary and the approach may be continued."
Therefore the relevant points are:
1) It is not necessary to "brief" the possibility of a GPWS warning to continue the approach - the pilot only needs to have assessed (in day VMC conditions) that there is no threatening terrain in the vicinity of the approach path.
2) In all other scenarios (night and/or IMC), any GPWS warning must be followed - even if familiar with the local area.
WRT the level-off altitude following a GPWS warning, the recovery actions state:
"Monitor radio altimeter for sustained or increasing terrain separation."
"When clear of terrain, slowly (my bolding) decrease pitch attitude and accelerate."
Remember that when the GPWS warning profile is flown, the aircraft will be at a very high pitch attitude with maximum thrust set. Even if initiated very early, a level-off that would not cause a very uncomfortable bunt would use a considerable ammount of airspace.
There is no "upper limit" to a GPWS recovery manoeuvre. While the highest MSA at Auckland is 3400 feet, even if the pilot initiated the recovery at this altitude it is likely that a much higher altitude would have resulted following the level-off (for the reasons already given). Our Limitations manual tells us that: "Pilots are authorised to deviate from their current ATC clearance to the extent necessary to comply with an EGPWS warning." Therefore, if a GPWS warning was received, it would supercede any previous ATC altitude instruction.
Further guidance from the manuals is that GPWS warnings take precedence over TCAS advisories.
Last edited by Three Bars; 12th Apr 2005 at 23:27.
Join Date: Oct 2002
Location: In Frozen Chunks (Cloud Cuckoo Land)
Age: 17
Posts: 1,521
Likes: 0
Received 0 Likes
on
0 Posts
Three Bars, note the word PRIOR
You must have verification PRIOR to the warning. How do you know what has set it off. I was once told of United airlines Jumbo flying underneath a QF jumbo in IMC (prior to TCAS). The UA jumbo did not maintain its altitude and came close to the underside of the QF one at 20000 odd feet setting the QFs GPWS off.
Now admittely its an unlikely scenario that a light a/c or some other object other than terrain would do this, but imagine you have just set up for approach, then told to Go around, mid go around you get a GPWS - which I dont think you could be expecting, nor with the high nose attitude can you see underneath you...... Would not the most conservative course of action be to carry out the GPWS maneouvre - especially seeing the emphasis being placed on it in QF training at the moment?
Anyway its all speculation, does anyone actually know the facts?
when flying under daylight VMC conditions prior to an obstacle or terrain warning
You must have verification PRIOR to the warning. How do you know what has set it off. I was once told of United airlines Jumbo flying underneath a QF jumbo in IMC (prior to TCAS). The UA jumbo did not maintain its altitude and came close to the underside of the QF one at 20000 odd feet setting the QFs GPWS off.
Now admittely its an unlikely scenario that a light a/c or some other object other than terrain would do this, but imagine you have just set up for approach, then told to Go around, mid go around you get a GPWS - which I dont think you could be expecting, nor with the high nose attitude can you see underneath you...... Would not the most conservative course of action be to carry out the GPWS maneouvre - especially seeing the emphasis being placed on it in QF training at the moment?
Anyway its all speculation, does anyone actually know the facts?
Join Date: Jan 2001
Location: NSW Australia
Posts: 233
Likes: 0
Received 0 Likes
on
0 Posts
Bluey,
I think you've missed the point of my posts.
I'm not trying to say anything about what happened in this incident. As usual, there is a lot of Monday morning quarterbacking going on here with a lot of misinformation spread about. For the benefit of other posters on this thread, I'm just trying to explain some of the heirarchy of requirements as they would have pertained to the QF crew.
Namely:
1) If a go-round instruction is received, it is flown.
2) If a GPWS is received (other than in day VMC) it must be flown.
3) The GPWS takes prioirity over ATC instructions.
4) A GPWS warning takes priority over a TCAS advisory (I don't even know if this was a factor in this case).
5) A GPWS recovery level-off will use quite a bit of airspace and probably exceeded the previous ATC clearance limit.
I have not made any judgements over what the crew did or did not do - I'm just trying to explain the decision-making process in such a situation. I'll wait to read the report with interest.
I think you've missed the point of my posts.
I'm not trying to say anything about what happened in this incident. As usual, there is a lot of Monday morning quarterbacking going on here with a lot of misinformation spread about. For the benefit of other posters on this thread, I'm just trying to explain some of the heirarchy of requirements as they would have pertained to the QF crew.
Namely:
1) If a go-round instruction is received, it is flown.
2) If a GPWS is received (other than in day VMC) it must be flown.
3) The GPWS takes prioirity over ATC instructions.
4) A GPWS warning takes priority over a TCAS advisory (I don't even know if this was a factor in this case).
5) A GPWS recovery level-off will use quite a bit of airspace and probably exceeded the previous ATC clearance limit.
I have not made any judgements over what the crew did or did not do - I'm just trying to explain the decision-making process in such a situation. I'll wait to read the report with interest.
Guest
Posts: n/a
3 Bars,
I dont think I am missing the point of your posts, you are missing the point of mine.
PROIR means exactly that.
Where CFIT accounts for a significant number of accidents GPWS alerts are not to be questioned.
"Airmanship is like common sense, you've either got it or you haven't."
I dont think I am missing the point of your posts, you are missing the point of mine.
PROIR means exactly that.
Where CFIT accounts for a significant number of accidents GPWS alerts are not to be questioned.
"Airmanship is like common sense, you've either got it or you haven't."
Join Date: Jan 2001
Location: NSW Australia
Posts: 233
Likes: 0
Received 0 Likes
on
0 Posts
Otto and Bluey,
Where have I ever said that they should not have followed the GPWS in this situation??????????????
In fact, I was explaining that in QF, GPWS warnings must be followed with only one exception - daylight VMC with prior assessment of visual terrain clearance.
I have reread my posts carefully to try and work out where there could be a misundertsanding and the best I can find is my quote:
In the above "in this instance (only)" means "except when in day VMC" not in the instance of the incident at Auckland.
Hope this clarifies things. We are arguing the same point here!!
Where have I ever said that they should not have followed the GPWS in this situation??????????????
In fact, I was explaining that in QF, GPWS warnings must be followed with only one exception - daylight VMC with prior assessment of visual terrain clearance.
I have reread my posts carefully to try and work out where there could be a misundertsanding and the best I can find is my quote:
2) GPWS warnings are to be followed in all instances except when in day VMC - in this instance (only) a GPWS warning does not need to be followed if a visual terrain assessment confirms that there is no danger to the aircraft.
Hope this clarifies things. We are arguing the same point here!!
Last edited by Three Bars; 13th Apr 2005 at 04:12.
Join Date: Oct 1999
Location: 20deg N, 35deg C
Posts: 92
Likes: 0
Received 0 Likes
on
0 Posts
QFA had just turned onto the 23 LLZ at 3000'. AA TWR had a VFR 'lost' over the city and heading towards final approach. QFA was maintained at 3000' and taken off the approach to the west to keep clear of the 'lost' VFR. The pilot reacted to a GPWS warning (still at 3000') and commenced a climb into the ANZ flight (at 4000') righthand downwind. TCAS then gave an RA requiring a left turn to pass behind ANZ. The reason for the GWPS remains a mystery that hopefully the investigation will resolve. Not a particularly nice experience for all involved.
TP
TP
Join Date: Oct 1999
Location: 20deg N, 35deg C
Posts: 92
Likes: 0
Received 0 Likes
on
0 Posts
Whatever... QFA however had to take avoiding action that involved a left turn to 'miss' ANZ. According to your comments it can't have been due to a TCAS RA, visual sighting perhaps or due to cues provided by TCAS (TA?)... What I do know is that they missed by not very much at all!!
The thing that concerns me most was that at 3000' QFA was above the minimum radar vectoring altitude and yet received a GPWS alert. The highest terrain in his vicinity was the top of Rangitoto Island (800' or there abouts) and as I work on this sector at present I will have to modify the way I operate!
As a footnote, I know that at Wellington the MRVA is also 3000' but rarely do they descend traffic below 4000' in IMC (especially jets) over terrain because they have been caught out there in the past with GPWS alerts.
TP
The thing that concerns me most was that at 3000' QFA was above the minimum radar vectoring altitude and yet received a GPWS alert. The highest terrain in his vicinity was the top of Rangitoto Island (800' or there abouts) and as I work on this sector at present I will have to modify the way I operate!
As a footnote, I know that at Wellington the MRVA is also 3000' but rarely do they descend traffic below 4000' in IMC (especially jets) over terrain because they have been caught out there in the past with GPWS alerts.
TP
Last edited by TinPusher; 13th Apr 2005 at 22:12.
Join Date: Aug 2001
Location: Sydney
Posts: 731
Likes: 0
Received 0 Likes
on
0 Posts
False GPWS alerts are not unknown. Unless you are day/VMC however, you follow them first and ask questions later.
Sounds like this guy may have been in the invidious position of having the GPWS telling him to climb and the TCAS telling him to descend... all while IMC. Not good...
Sounds like this guy may have been in the invidious position of having the GPWS telling him to climb and the TCAS telling him to descend... all while IMC. Not good...
Join Date: Sep 2002
Location: Here and there.
Posts: 203
Likes: 0
Received 0 Likes
on
0 Posts
OhForShure
There is no SOP, it is one of those situations where you have to work out what is most lilely to be the worst case and do the procedure for that.
For me I would follow a GPWS over a TCAS any time.
There is no SOP, it is one of those situations where you have to work out what is most lilely to be the worst case and do the procedure for that.
For me I would follow a GPWS over a TCAS any time.
Last edited by RaTa; 14th Apr 2005 at 11:45.
Makes sense. If you descend against a GPWS you WILL eventually hit an obsticle. If you climb against an RA you MIGHT hit an aeroplane. I know which option I'd go for.
Join Date: Feb 2005
Location: New Zealand
Posts: 5
Likes: 0
Received 0 Likes
on
0 Posts
Talking to ATC they said press got it wrong and it was 2 x b767.
QFA on 23R LLZ/DME and ANZ downwind r/h . Light a/c tracks across zone, QFA sent round right turn climb to 3000ft.
GPWS warning sounded QFA advises climbing to 5000ft.
weather scattered shrs in area but okay.
Light a/c flown by off duty b767 pilot (rumour - unconfirmed but very strong)
25nm MSA R180 west to R360 2800
R360 east to R180 3400
QFA on 23R LLZ/DME and ANZ downwind r/h . Light a/c tracks across zone, QFA sent round right turn climb to 3000ft.
GPWS warning sounded QFA advises climbing to 5000ft.
weather scattered shrs in area but okay.
Light a/c flown by off duty b767 pilot (rumour - unconfirmed but very strong)
25nm MSA R180 west to R360 2800
R360 east to R180 3400
Join Date: Jan 2003
Location: more East than usual
Posts: 51
Likes: 0
Received 0 Likes
on
0 Posts
The aircraft was at 3000', skirting some wx and in cloud and rain. GPWS went off, and although there's only 400' to MSA, you MUST follow the procedure, and once you've got GA thrust set and 20 deg nose up, you ain't gonna stop it in 400'! If you did you'd be peeling people off the roof! There's no exception where you can trickle the thrust on and climb to MSA! Besides, if the GPWS is going off you can't trust your altimeters!
ATC advised QF of conflict and they turned, they could see the NZ aircraft on their TCAS, and it turned from blue to red, but they never got a RA. The climb wasn't intended to 5000', but once the appropriate procedure was followed that was what they had.
It looks like a spurious GPWS at this stage, possibly due to the rain.
ATC advised QF of conflict and they turned, they could see the NZ aircraft on their TCAS, and it turned from blue to red, but they never got a RA. The climb wasn't intended to 5000', but once the appropriate procedure was followed that was what they had.
It looks like a spurious GPWS at this stage, possibly due to the rain.
